<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="http://hongweizhiyuan.oss-cn-hangzhou.aliyuncs.com/layui/css/layui.css"/>
</head>
<body>

<script src="http://hongweizhiyuan.oss-cn-hangzhou.aliyuncs.com/layui/layui.js"></script>
<script>
    //一般直接写在一个js文件中
    layui.use(['layer', 'form'], function(){
        var layer = layui.layer
            ,form = layui.form;

        var a = 1;
        layer.msg('Hello World');
    });
</script>
</body>
</html>